Recent activity

The geomagnetic field was quiet to unsettled on May 19. Solar
wind
speed ranged between 422 and 596 km/sec. A high speed stream from CH166 was observed beginning early on May 20 at ACE.

Solar flux measured at 20h UTC on 2.8 GHz was 84.7. The planetary
A
index was 11 (STAR Ap - based on the mean of three hour interval ap
indices: 11.0).
Three hour interval K indices: 23322233 (planetary), 23322333 (Boulder).

The background x-ray flux is at the class A7 level.

At midnight there were 2 spotted regions on the visible solar disk. The solar flare activity level was very low. No C class
events were recorded during the day.

Region 10759 was quiet and stable and will rotate out of view at the northwest limb today.
New region 10765 rotated into view at the northeast limb on May 18 and was numbered by SEC the next day. The region decayed
slowly on May 19 and could become spotless today.

Coronal mass ejections (CMEs)

May 18-19: No obviously fully or partly potentially geoeffective CMEs were observed.May 17: A very faint and slow full halo CME was observed after an M1.8 flare in region 10763 early in the day. This CME
could reach Earth early on May 20.

Coronal holes

A recurrent coronal hole (CH166) in the northern hemisphere was in an
Earth facing position on May 17.

Processed SOHO/EIT 284 image at 01:06 UTC on May 20. The
darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be unsettled to minor storm on May 20 due to a high speed stream from CH166 and a weak CME. Quiet to unsettled is likely on May
21-23.

Coronal holes (1)

Coronal mass ejections (2)

M and X class flares (3)

1) Effects from a coronal hole could reach Earth
within the next 5 days. When the high speed stream has arrived
the color changes to green.
2) Material from a CME is likely to impact Earth within 96 hours.
3) There is a possibility of either M or X class flares within the next
48 hours.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation
along
east-west paths over high and upper middle latitudes is very poor.
Propagation along long distance north-south paths is poor to fair.
Trans
Atlantic propagation conditions are normally monitored every night on
1470 kHz. Dominant stations tonight: Radio Cristal del Uruguay and Radio Rafaela (Argentina). On other frequencies propagation was
best from Brazil (930 Rádio
Metropolitana, 740 Rádio Sociedade, 1430 Rádio Clube Paranaense and 1100 Rádio Globo had the best signals) and Argentina.

Data for all numbered solar regions according to the Solar Region
Summary provided by
NOAA/SEC. Comments are my own, as is the
STAR spot count (spots observed at or inside a few hours before
midnight) and data for regions not numbered by SEC or where SEC has
observed no spots.
SEC active region numbers in the table below and in the active region
map above are the historic
SEC/USAF numbers.

Active region

Date numbered

SEC
spot
count

STAR
spot
count

Location at midnight

Area

Classification

Comment

10759

2005.05.08

1

1

N12W75

0270

HHX

classification was HKX at midnight

10763

2005.05.12

2

S16W35

0010

BXO

spotless

10765

2005.05.19

1

1

N09E65

0030

HSX

formerly region S550
classification was AXX at midnight, area 0010

S548

2005.05.17

S13W14

plage

S549

2005.05.18

S12W21

plage

Total spot count:

4

2

SSN:

34

22

Monthly solar cycle data

Month

Average solar
flux at Earth

International sunspot number

Smoothed sunspot number

2000.04

184.2

125.5

120.8
cycle 23 sunspot max.

2000.07

202.3

170.1

119.8

2001.12

235.1

132.2

114.6 (-0.9)

2004.03

112.0

49.1

47.1 (-2.2)

2004.04

101.2

39.3

45.5 (-1.6)

2004.05

99.8

41.5

43.8 (-1.7)

2004.06

97.4

43.2

41.6 (-2.2)

2004.07

119.1

51.1

40.2 (-1.4)

2004.08

109.6

40.9

39.2 (-1.0)

2004.09

103.1

27.7

37.5 (-1.7)

2004.10

105.9

48.0

35.9 (-1.6)

2004.11

113.2

43.5

(34.8 predicted, -1.1)

2004.12

94.5

17.9

(33.4 predicted, -1.4)

2005.01

102.2

31.3

(30.9 predicted, -2.5)

2005.02

97.2

29.1

(28.3 predicted, -2.6)

2005.03

89.9

24.8

(26.5 predicted, -1.8)

2005.04

86.0

24.4

(24.6 predicted, -1.9)

2005.05

106.1 (1)

45.2 (2)

(22.0 predicted, -2.6)

1) Running average based on the daily 20:00 UTC observed solar flux
value at 2800 MHz.
2) Unofficial, accumulated value based on the Boulder (NOAA/SEC)
sunspot number. The official international sunspot number is typically
30-50% less.

This report has been prepared by Jan
Alvestad. It is based partly on my own observations and analysis,
and
partly on data from some of these solar data sources.
All time references are to the UTC day. Comments and suggestions are
always welcome.